Gas detector and signal device



Sept. 13, 1932. L. w. M CAlN ET AL 1,876,706

GAS DETECTOR AND SIGNAL DEVICE Filed July 30, 1927 2 Sheets-Sheet 1 Sept. 13, 1932. L. w.- Ma cA|N ET AL 1,876,706

GAS DETECTOR AND SIGNAL DEVICE Filed July so. 192'? 2Sheets-Sheet 2 I 8 z I @513 2% 61mm??? if 4&6-

Patented Sept. 13, 1932 UNITED STATES PATENT OFFICE LLOYD W. MACCAIN, OF BRONX, AND EDMOND F. WEBB, OF NEW YORK, N. Y., ASSIGNORS, BY MESNE ASSIGNMENTS, TO SAID LLOYD W. MACCAIN GAS DETECTOR AND SIGNAL DEVICE Application filed July 30, 1927. Serial No. 209,589.

This invention relates to gas-detecting and "fully protected against outside disturbing agencies, such as dust Or -moisture, but sensitive to the presence of explosive danger gases. Another object includes the provision of thermostatic control, or of a plurality of thermostatic controls, arranged and constructed to be operated in consequence of the presence of hydrogen or a hydrogen containing gas. We further provide a plurality of circuits each controlled thermostatically and so arranged as to be rendered effective to maintain a temperature control device and a signal device in consequenceof a drop in temperature and in response to the presence of the danger gas in predetermined percentages.

We also provide means for instantly testing the mechanism without in any manner intefrfering with the normal functions there 0 Other objects will appear hereinafter andv we obtain these objects by the construction illustrated in the accompanying drawings in I which Fig. 1 is a sectional view of a construction embodying the principles of our invention.

Fig. 2 is a diagrammatic view of the circuits and thermostats for control of the temperature regulating and signal devices.

Fig. 3 isa section taken on the line 3-3 of Fig. 1.

Fig. 4. is a view in side elevation of the thermostat support.

Fig. 5 is an end view thereof.

Fig. 6 is a view on the line 6-6 of Fig.3

looking in the direction of the arrows.

Fig. 7 is a top plan view of a portion of the thermostat showing the catalytic agencies and holder thereon and Fig. 8 is a view of the same without said agencies and holder.

Like numerals of refercncerefer to the similar parts throughout the several views.

It is among the prime purposes of our invention to provide an efiicient detector andalarm device which is comparatively simple in construction, but which is sensitive to fractional'percentages of danger gases, and which is practically independent of sudden and wide external temperature or humidity changes. The device is moreover self-controlled and automatic in its functions and requires practically no attention to maintain it at its height of efficiency.

Referring now to the drawlngs wherein we have illustrated a preferred form of construction, but we do not desire to be understood as having thus limited ourselves to the exact form shown, we provide a substantially self-contained device, comprising an outer casing 10 preferably, though not necessarily, tubular in form and provided at the top and bottom, respectively, with screw threads 11 and 12 on which fit the screw caps 14 and 15. The tubular casing and caps, which form an enclosed receptacle, may be of any suitable material, such as brass or other noncorrosible metal or composition. This enclosed receptacle is provided with a suitably sealed tubule 16 through which pass and in which are sealed the electric conductors 17 for operating the mechanism to be explained presently.

A number of holes 18, at a suitable position in the casing 10, afford entrance to the dangerous gas by which the alarm signal is caused to function. These holes are protected by a fine mesh (about brass gauze 18 which is soldered or otherwise secured onto the caslng.

A supporting stem 19 is secured in suitable manner as by screw threads on the lower cap 15, to extend into the chamber of the enclosed receptacle. This stem supports the operating mechanism which comprises a tubular casing 20, a top plug 21, a bottom cap 22 and the insulation base 23 with its temperature control thermostat 24, and the signal operating thermostat .25 and associated parts about to be described. The receptacle for the operating mechanism is made of an suitable material such as brass and the base ismade of a nonconducting material such as, a phenolic condensation product or the like.

Casing 20 is provided with a comparatively 'large number of holes 26, which are preferthe cap 22 by proper holding means, as screws 30. As is best shown by Fig. 4, this base contains a stair-step cavity. On the-lower step 31 thereof is mounted, by screws 32, the vertical arm 24 of the temperature control thermostat 24. This arm comprises the inner high coeflicient expansion metal 33 and the outer lower coeflieient expansion metal 33' with the contact plate 34 secured at the free end of the arm 24. A set screw 35 on plate 36 provides means for suitable adjustment. This plate is secured to the insulation block 23 by screws 37.

On the second step 40 of block 23 there is fastened the adjustment screw base 41 by screws 42. Base 41 carries the alarm thermostat screw 43 for properly adjusting the distances between said screw and the alarm thermostat contact 44 of the alarm thermostat 25. The thermostat arm 50 is composed of an outer high coefficient metal or alloy 45 and an inner metal 45 of lower coefiicient of expansion. This arm is properly fastened onto the upper stair-step 46 by a screw 47, or the equivalent. At a suitable position on said arm we fasten the catalytic agent preferably in the form of tablets 48. These tablets are held in a frame 49 which is fastened to the thermostat arm 50 by screws 51. A

skeleton shield 52 keeps the catalytic tablets from falling out.

The tablets 48 may be made of various substances and in various ways which are well known to those skilled in the art. The following method is given as an example. Tablets of the required shape and size are formed of a light porous material, as meer schaum. These are saturated with a solution of platinic chloride and dried. The platinic chloride is then reduced with illuminating gas at a temperature of about (1., leaving finely divided platinum black in the tablet. Whilethis is a satisfactory method of forming the tablets it forms no part of the for a definite temperature, will remain closed so long as the said temperature is below the predetermined temperature, by reason of the thermostatic component metals, or metal alloys, described above. From an inspection of ig. 2, it is evident that the light 60 will glow or remain hot 50 long as the thermostat 24 and, therefore, the light circuit remains closed. When, however, the adjusted degree of temperature has been reached the temperature regulating thermostat 24 will open'and break the light or heater circuit. By this arrangement a substantially constant temperature and dry atmosphere is maintained within the operative chamber of our device.

The presence of hydrogen or methane within the operative chamber by. reason of chemical action will cause a rise of temperature within the entire chamber because of the repeated small explosion of the gas about the make and break of thermostat 24, or the temperature rise will be merely local by reason of the catalytic agency on the thermostat member 50 of the alarm thermostat 25. In

either case the contact of the alarm thermostat will'be closed and the alarm circuit established to operate a suitable alarm signal or signals 66. A test switch 62 in the light or heating circuit will permit the heating circuit to be controlled at the will of the operator to test the device.

It will be observed that by our construction and arrangement of the protected perforations with the operative mechanism within the operative chamber no explosions will be propagated to the outside of said chamber.

This is a distinct advantage of our device over other devices known to us, which we believe makes our well as reliable.

We have found, from actual tests, that our device is very reliable, and that it can be regulated to detect danger gases within small percentages. Although we prefer the use of a catalyst as shown and described, we have discovered that the device operates on explosive gas mixture even without the catalytic agencies. This is because of the repeated small explosions, which take place within the operative chamber in the presence of the danger gas to cause a temperature risesufficient to close the alarm circuit. With the use of a catalyst however the device is very sensitive as heat is imparted directly tothe device absolutely safe as alarm thermostat arm 50 for closing the alarm circuit. 7

Having now described our invention, what we claim as new and useful, and desire to secure by Letters Patent, is: I

1. A gas detector and signal device comprising a casing having perforations, a metallic screen and a fibrous cover over said perforations, an insulation base within said casing, thermostat arms mounted on said base, a receptacle mounted on one of said arms and catalytic agencies in said receptacle whereby said thermostat arm is operated in response to the presence of a predetermined percentage of hydrogen, and heating means controlled by the other thermostat arm for maintaining the atmosphere about said base and arms at a substantially constant temperature.

2. A device for detecting the presence of a combustible gas in an atmosphere comprising, in combination, a main casing provided with openings phere to be tested, a second casing within said main casing, said second casing having passages in the walls thereof, a heater device within said main casing, temperature responsive means within said second casing for controlling said heater device to cause said heater tomaintain the interior of the second casing at a substantially constant temperature, a signal device without said main casing and means within the second casing responsive to the presence of a combustible gas for controlling the operation of the signal device.

3. A device for detecting the presence of a combustible constituent in an atmosphere comprising a casing, said casing being provided with openings, a source of current, a

heating device, a circuit including said heat- I ing device, said source of current,- and a temperature responsive device within said casing adapted to open said circuit when a predetermined temperature is reached, a signal device, a second temperature responsive device in said casing, said second temperature responsive device being in circuit with'said source of current and said signal device and means for heating said second temperature responsive device by the presence of a combustible gas.

4. A device as claimed in claim 3 provided with means for supplying current to said heating'device while the circuit is opened by the first named temperature responsive dev1ce.

5. A device for detecting the presence of a combustible gas in an atmosphere comprising a casing provided with perforations, a base of insulating material within said casing, a heater within said casing, a circuit for supplying current to said heater includin a temperature responsive circuit bre er mounted on said insulating base, a signal without said casing, a second temperature refor the passage of the atmos-.

sponsive circuit breaker on said insulating for said signal, a temperature responsive circuit opening and closing means in said circuit, a catalytic agent adjacent said temperature responsive means, a protective and heat insulating enclosure surounding said temperature responsive means, said enclosure being provided with passages for permitting the entrance of the atmosphere to be tested,

and means for maintaining the temperature 6 within the enclosure substantially constant.

8. A gas detector and signal device comprising a casing provided with openings therein, means for preventing the propagation of an explosion through said openings, top and bottom closure members for said casing, an insulating base member having a stepped cavity within said casing, a plurality of temperature responsive circuit closing members on the steps'of' said base member, a catalyst mounted 'on one of said temperature responsive members, a signal in circuit with said temperature responsive member and a heating element within said casing and in circuit with another of said temperature responsive elements.

9. A device for closing an electric circuit and to operate a signal device in response to the presence of a combustible gas comprising a casing provided with openings and shields for-said openings, a bi-metallic thermostatic metal havmga catalyst held on the surface of one of said metals, and a heater within said casing for maintaining a substantially uniform temperature around said catalyst andits thermostat, and a temperature responsive iwitch within said casing for controlling said eater.

In testimony whereof we have hereunto set" our hands on this 27th day of July A. D., 1927.

'LLOYD W. MAoGAIN.

EDMOND F. WEBB. 

